1. ➢ Scapula:
• In anatomy, the scapula (plural scapulae or scapulas), also known as the shoulder bone, shoulder
blade, wing bone or blade bone, is the bone that connects the Humerus (upper arm bone) with the
clavicle (collar bone).
• The scapula, also known as the shoulder blade, is a flat triangular bone located at the back of the trunk
and resides over the posterior surface of ribs two to seven.
• The scapula, along with the clavicle and the manubrium of the sternum, make up the pectoral (shoulder)
girdle which connects the upper limb of the appendicular skeleton to the axial skeleton.
✓ Type of Bone:
• Flat bone developing by cartilaginous ossification.
✓ Anatomical Position:
• It lies on posterolateral aspect of chest wall covering the back of the ribs 2 to 7
• Its medial border lies parallel to vertebral column and 5cm away from the spine.
• The coracoid process project forward and slightly laterally below the junction between the lateral 1/4th
and the medial 3/4th
of the clavicle.
2. ✓ Osteology:
•
• Surfaces:
1. Costal Surface or Subscapular Fossa:
The costal (anterior) surface of the scapula faces the ribcage. It contains a large concave depression
over most of its surface, known as the subscapular fossa. The subscapularis (rotator cuff muscle)
originates from this fossa
2. Dorsal Surface:
The prominent spine of scapula divides the surface into a smaller supra-spinous fossa and a
larger infra-spinous fossa. The depth of the supra-spinous fossa is filled by the supraspinatus
muscle
• Borders:
1. Superior Border
It is thin and shorter. It presents the suprascapular notch near the root of the coracoid process.
The superior border extends from the superior angle laterally towards the coracoid process.
2. Lateral Border
This is thick and presents infra-glenoid tubercle at the upper end. The lateral or axillary border
runs from the inferior angle to the lateral angle of the scapula.
3. 3. Medial Border
This is thin and extends from superior to inferior angle. With the arm resting by the side, the
medial or vertebral border runs almost parallel to the spinal column.
• Angles:
1. Superior Angle is covered by trapezius
2. Inferior angle is covered by the latissimus dorsi. It moves forwards round the chest, when the
arm is abducted. Palpation of the inferior angle provides a convenient method for following the
movement of the scapula during arm motion.
3. Lateral or Glenoid angle is broad and bears the glenoid cavity or fossa, which is directed
forward, laterally and slightly upwards.
• Fossae of the scapula:
1. Subscapular Fossa: It is concave ventral aspect of scapula.
2. Supra spinous fossa: it is area of dorsal surface lying above the spine.it also include the
upper surface of spine.
3. Infra-spinous fossa: it is area of dorsal surface lying below the spine. it also include the
lower surface of spine.
• Processes:
1. Spine or Spinous Process is a triangular plate of bone with 3 borders and 2 surfaces. It
divides the dorsal surface of the scapula into supra-spinous and infra-spinous fossae. The
posterior border is called the crest of the spine which has upper and lower lips.
2. The Acromion Process has 2 borders, medial and lateral; 2 surfaces and a facet for clavicle.
3. The Coracoid Process Pointing laterally forward, it, together with the acromion, serves to
stabilize the shoulder joint.
4. • Notches of scapula:
✓ Supra scapular notch: it lies at the lateral end of superior border close to the root of the coracoid
process.
✓ Spino-glenoid notch: it lies between the lateral free border of the spine and the glenoid cavity.
✓ Circumflex scapular notch: it is a groove on a dorsal aspect of the lateral border produced by
circumflex scapular artery.
• Side determination:
1. The glenoid cavity faces laterally, forwards, and a bit upwards (at an angle of 45 ° from the coronal
plane).
2. The coracoid process is directed forwards.
3. The shelf-like spinous process is directed posteriorly.
• Articulation: The scapula has two main articulations:
1. Gleno-humeral joint – between the glenoid fossa of the scapula and the head of the Humerus.
2. Acromioclavicular joint – between the acromion of the scapula and the clavicle.
• Muscles:
1. Subscapularis arises from the medial 2/3rds of the subscapular fossa.
2. Supraspinatus arises from medial 2/3rds of supraspinous fossa including upper surface of the
spine
3. Infraspinatus arises from medial 2/3rds of infraspinous fossa, including lower surface of spine.
4. Deltoid arises from lower border of the crest of spinthe e and from lateral border acromion.
5. Latissimus Dorsi lower fibres originate from inferior angle of scapula
6. Trapezius is inserted into the upper border of the crest of the spine and into medial border of the
acromion.
7. Serratus anterior is inserted along the medial border of costal surface
8. The long head of biceps brachii arises from supra-glenoid tubercle and the short head from the
lateral part of the tip of the coracoid process.
9. Coraco-brachialis arises from medial part of tip of coracoids process
5. 10. Pectoralis minor is inserted into the medial border and superior surface of coracoids process.
11. The long head of triceps arises from infra-glenoid tubercle
12. Teres minor arises from upper 2/3rds of rough strip on the dorsal surface along the lateral border.
13. Teres major arises from lower 1/3rd of rough strip on the dorsal aspect of lateral border
14. Levator scapulae is inserted along the dorsal aspect of the medial border, from superior angle up
to root of spine.
15. Rhomboideus minor is inserted into medial border (dorsal aspect) opposite to root of spine
16. Rhomboideus major is inserted into the medial border (dorsal aspect) between the root of spine
and inferior angle
17. Inferior belly of omohyoid arises from upper border near supra scapular notch.
• Ligaments:
1. The margin of glenoid cavity gives attachment to the capsule of shoulder joint and to the
glenoid labrum
2. The margin of the facet on the medial aspect of the acromion gives attachment to the capsule of
the acromioclavicular joint
3. The coracoacromial ligament is attached to the lateral border of the coracoids process and to
the medial side of the tip of the acromion process
4. The coracohumeral ligament is attached to the root of the coracoids process.
5. The coracoclavicular ligament is attached to the coracoid process.
6. The suprascapular ligament bridges across the suprascapular notch and converts it into a
foramen which transmits the suprascapular nerve. The suprascapular ligament lie above the
ligament.
7. The spino-glenoid ligament bridges the spino-glenoid notch. The suprascapular vessels and
nerve pass to it.
8. The acromioclavicular ligament connects the distal end of the clavicle to the acromion and
provides horizontal stability
• Bursa: There are two major bursae:
1. Scapulo-thoracic Bursa, between the serratus and the thorax, and
2. Sub-scapularis Bursa, between the subscapularis and the serratus.
• Clinical Notes:
1. Scapular Fracture:
✓ High-energy, blunt trauma injuries, such as those experienced in a motorcycle or motor vehicle
collision or falling from a significant height, can cause a scapula fracture. Other major injuries
often accompany scapular fractures, such as fractures in the shoulder, collarbone and ribs, or
damage to the head, lungs, or spinal cord.
✓ One or more parts of the scapula may be fractured.
6. Scapular body (50% to 60% of patients)
Scapular neck (25% of patients)
Glenoid
Acromion
Coracoid
✓ The most common symptoms of a scapula fracture include:
• Extreme pain when you move the arm
• Swelling around the back of the shoulder.
2. Dropped Shoulder:
✓ The position of the scapula on the posterior wall of the thorax is maintained by the tone and
balance of the muscles attached to it.
✓ If one of these muscles is paralyzed, the balance is upset as in dropped shoulder which
occurs with paralysis of the trapezius muscle.
✓ Winged scapula caused by paralysis of the serratus anterior.
